First plugin doesn't work at other pc

I just finished my first plugin (PbMineExp), it works fine on my pc but it gives an error on my friends pc who runs everything on the same version of as I do.
This is his error:

Code:

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14:28:09 [INFO] Starting minecraft server version 1.2.5
14:28:09 [INFO] Loading properties
14:28:09 [INFO] Starting Minecraft server on 192.168.2.5:25565
14:28:09 [WARNING] **** SERVER IS RUNNING IN OFFLINE/INSECURE MODE!
14:28:09 [WARNING] The server will make no attempt to authenticate usernames. Be
ware.
14:28:09 [WARNING] While this makes the game possible to play without internet a
ccess, it also opens up the ability for hackers to connect with any username the
y choose.
14:28:09 [WARNING] To change this, set "online-mode" to "true" in the server.pro
perties file.
14:28:09 [INFO] This server is running CraftBukkit version git-Bukkit-1.2.5-R1.0
-b2149jnks (MC: 1.2.5) (Implementing API version 1.2.5-R1.0)
14:28:09 [SEVERE] Could not load 'plugins\PbMineExp.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.UnsupportedClassVersionError
: me/postbag/pbmineexp/PbMineExp : Unsupported major.minor version 51.0
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.j
ava:150)
        at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.
java:305)
        at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager
.java:230)
        at org.bukkit.craftbukkit.CraftServer.loadPlugins(CraftServer.java:207)
        at org.bukkit.craftbukkit.CraftServer.<init>(CraftServer.java:183)
        at net.minecraft.server.ServerConfigurationManager.<init>(ServerConfigur
ationManager.java:53)
        at net.minecraft.server.MinecraftServer.init(MinecraftServer.java:156)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:422)
        at net.minecraft.server.ThreadServerApplication.run(SourceFile:492)
Caused by: java.lang.UnsupportedClassVersionError: me/postbag/pbmineexp/PbMineEx
p : Unsupported major.minor version 51.0
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClassCond(Unknown Source)
        at java.lang.ClassLoader.defineClass(Unknown Source)
        at java.security.SecureClassLoader.defineClass(Unknown Source)
        at java.net.URLClassLoader.defineClass(Unknown Source)
        at java.net.URLClassLoader.access$000(Unknown Source)
        at java.net.URLClassLoader$1.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(Unknown Source)
        at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.
java:41)
        at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.
java:29)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Unknown Source)
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.j
ava:139)
        ... 8 more

what happend? because everything works fine on my pc :\

plugin.yml

Code:

name: PbEssential
main: me.postbag.pbmineexp.PbMineExp
version: 1.6
authors:
  - Postbag

PbMineExp.java

Code:

package me.postbag.pbmineexp;
 
import java.util.logging.Logger;
 
import org.bukkit.plugin.java.JavaPlugin;
 
 
 
 
public class PbMineExp extends JavaPlugin{
   
    public static final Logger log = Logger.getLogger("Minecraft"); //Hiermee kunnen we berichten versturen naar de console.
   
        public void onEnable(){ //Deze code word uitgevoerd als de plugin word aangezet.
            log.info("PbMineExp is enabled.");
            new PbMineExpBlockListener(this);
        }
   
 
    public void onDisable(){ //Deze code word uitgevoerd als de plugin word afgesloten.
    log.info("Thanks for using PbMineExp.");        //We hoeven de events niet te deregistreren, dit gebeurt automatisch.
    }
   
    /*public boolean onCommand(CommandSender sender, Command command, String commandLabel, String[] args){
        //////////////////////////////////////////////////////////////////////
             
        ////////////////////////////////////////////////////////////////////////       
       
        return false;
    }*/
   
}

PbMineExpBlockListener.java

Code:

package me.postbag.pbmineexp;
 
import org.bukkit.Material;
import org.bukkit.block.Block;
import org.bukkit.entity.EntityType;
import org.bukkit.entity.ExperienceOrb;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.block.BlockBreakEvent;
import org.bukkit.event.block.BlockPlaceEvent;
 
 
 
public class PbMineExpBlockListener implements Listener{
   
    public static PbMineExp plugin;
 
    public PbMineExpBlockListener(PbMineExp instance)
    {
        plugin = instance;
        plugin.getServer().getPluginManager().registerEvents(this, plugin);
    }
 
    @EventHandler
    public void onBlockPlace(BlockPlaceEvent event){
       
        Player player = event.getPlayer();
        Block block = event.getBlock();
        Material mat = block.getType();
       
    }
   
    @EventHandler
    public void onBlockBreak(BlockBreakEvent event){
        Player player = event.getPlayer();
        Block block = event.getBlock();
        Material mat = block.getType();
        ExperienceOrb orb = block.getWorld().spawn(block.getLocation().add(0.5, 0.5, 0.5), ExperienceOrb.class);
       
        ////////////////// shovel/hand
       
        if(event.getBlock().getType().equals(Material.SAND)){
            orb.setExperience(3);
          /*float explosionPower = 50F;
            block.getWorld().createExplosion(block.getLocation(), explosionPower);*/
        } 
       
        if(event.getBlock().getType().equals(Material.GRAVEL)){
            orb.setExperience(3);
        }
       
        if(event.getBlock().getType().equals(Material.DIRT)){
            orb.setExperience(3);
        }
       
        if(event.getBlock().getType().equals(Material.GRASS)){
            orb.setExperience(3);
            /*if(event.getPlayer().getName().equals("Postbag")){
                block.getWorld().spawnCreature(block.getLocation(), EntityType.CREEPER);
            }*/
        }       
       
        if(event.getBlock().getType().equals(Material.SOUL_SAND)){
            orb.setExperience(3);
        }
       
        ////////////////////////// hand/other tools
       
        if(event.getBlock().getType().equals(Material.GLOWSTONE)){
            orb.setExperience(12);
        }   
       
        ////////////////////////// hatchet
       
        if(event.getBlock().getType().equals(Material.WOOD)){
            orb.setExperience(6);
        }
       
        ///////////////////////// pickaxe
       
        if(event.getBlock().getType().equals(Material.SANDSTONE)){
            orb.setExperience(7);
        }
       
        if(event.getBlock().getType().equals(Material.STONE)){
            orb.setExperience(5);
        }
       
        if(event.getBlock().getType().equals(Material.NETHERRACK)){
            orb.setExperience(4);
        }
       
        if(event.getBlock().getType().equals(Material.COAL_ORE)){
            orb.setExperience(8);
        }
       
        if(event.getBlock().getType().equals(Material.IRON_ORE)){
            orb.setExperience(10);
        }
       
        if(event.getBlock().getType().equals(Material.LAPIS_ORE)){
            orb.setExperience(20);
        }
       
        if(event.getBlock().getType().equals(Material.GOLD_ORE)){
            orb.setExperience(25);
        }
       
        if(event.getBlock().getType().equals(Material.DIAMOND_ORE)){
            orb.setExperience(40);
        }
       
        if(event.getBlock().getType().equals(Material.REDSTONE_ORE)){
            orb.setExperience(20);
        }
       
        //////////////Fun block
       
        if(event.getBlock().getType().equals(Material.SPONGE)){
            orb.setExperience(5000);
            player.sendMessage("Because I love you.");
            player.getWorld().spawnCreature(player.getLocation(), EntityType.LIGHTNING);
        }
       
        //////////////////////////
       
       
    }
}

 

You compiled with a higher version then your server is running, Also offline mode is never a good idea.

 

So how do i fix it? :\

 

recompile with the version your server is using or change the version the server is using. Most plugins are compiled with Java 6.

 

i think i compiled everythig using Java 7, how do i compile it using java 6?(i use ecplise)

 

The problem might be simpler than that. I believe the craftbukkit server he is running vs the client he is running do not match the compiled craftbukkit version. ensure all 3 are matching versions (Craftbukkit 1.2.5-R1.0.jar matches the plugin included craftbukkit far, and the client is running 1.2.5) Worst case scenario, re-download the latest craftbukkit release, and install both Java releases (1.6 and 1.7) as well as 32 bit and 64 bit (depending on the OS)

 

ProjectExplorer->Right click on your Project->Build Path->Configure Build Path...->double-click JRE System Library->chose the 1.6 jdk

EDIT: your friend could also change the batch which is starting the server if he has 1.7 installed to
[...]jre7\bin\java.exe[...]

 

Thanks guys!
you're awesome, all of you
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